1. Field of the Invention
This invention relates to a display apparatus for a vehicle, projecting a picture displayed on an image source onto the member of projection in front of a vehicle driver for superimposing a virtual image of the picture on a front view looked through a windshield from an eye point within the vehicle.
2. Description of the Related Art
A projection display apparatus, called a head up display (HUD), is applied to display information, which can not be displayed on an instrument panel because of no extra rooms for increasing contents and variety of information requested by a vehicle driver at driving these years, as a virtual image on a windshield by superimposing the virtual image on a front view looked through the windshield.
It is known that major information, which a human receives from outside, is by visual sense so that importance of visibility is extremely increased when driving a vehicle. Faster perceiving an obstacle existing in a travelling direction, more marginally a vehicle driver can take action therefor. For the reason, a night vision system for driving at night to support safe driving by insuring visibility at night or in a bad visual condition is on the market.
The night vision system is structured with an infrared camera mounted on a front portion of a vehicle, a computer and the HUD mentioned above. Displaying a monochrome virtual image, detected by the infrared camera to detect infrared rays radiated by an object, with the HUD in front of a vehicle driver, makes the vehicle driver perceive an invisible obstacle in the dark or an obstacle ahead the vehicle in a bad visual condition by rain or fog.
Reflecting image light ray of the HUD at a member of projection such as a combiner or a windshield, the HUD makes the vehicle driver perceive the image in driving view area. Thereby, an angle moving a visual axis downwardly to see an image can be decreased as compared with seeing meters or a usual image so that a time for moving a visual axis can be shortened. Thereby, position of display can be in the distance from a vehicle driver so that focusing eyes can be made easy when moving a visual axis from a front view to the image. When a distance between a vehicle going ahead is small or a distance between an obstacle such as a human, an animal or the like is small, displaying an image hides a front view so that a vehicle driver may be hindered from seeing the front view.
To overcome the above drawback of a usual display system, one object of this invention is to provide a display apparatus for a vehicle which can display a virtual image without hindering from seeing a front view.
How to Attain the Object
In order to attain the objects, a display apparatus for a vehicle according to this invention, as shown in a basic block diagram of FIG. 1, wherein projecting a picture displayed on an image source onto a member of projection in front of a vehicle driver for superimposing a virtual image of the picture on a front view looked through a windshield from an eye point within the vehicle, includes a storage device 21b for storing a distance information of superimposed viewing, the distance information of superimposed viewing indicating a distance between an obstacle existing in the view ahead the vehicle and the vehicle whereby the virtual image and the obstacle are viewed as a superimposed front view from the eye point; distance measuring means 40 for measuring a distance between the vehicle and the obstacle; judging means 21a1 for judging whether or not the virtual image is superimposed on the obstacle based on the distance measured by the distance measuring means 40 and the distance information of superimposed viewing stored in the storage device 21b; and control means 21a2 for controlling to stop the projection of the picture when the judging means 21a1 judges that the virtual image is superimposed on the obstacle.
In the display apparatus for a vehicle as mentioned above, a distance information of superimposed viewing indicating a distance between an obstacle in the view ahead the vehicle and the vehicle, in which the virtual image and the obstacle are viewed as a superimposed front view from an eye point, is stored in the storage device 21b. When a distance between the vehicle and the obstacle is measured by the distance measuring means 40, it is judged by the judging means 21a1 whether or not the virtual image is superimposed on the obstacle based on the distance measured by the distance measuring means 40 and the distance information of superimposed viewing stored in the storage device 21b. Controlling to stop the projection of the picture onto a member of projection is done by control means 21a2 when it is judged that the virtual image is superimposed on the obstacle. Thus, when an obstacle which is seen in a front view and superimposed by the virtual image in the view from the eye point is detected, projecting a picture onto the member of projection is stopped so that a display apparatus for a vehicle, which does not fail to perform essential purpose of the display apparatus for awaking speedily visual information in driving without preventing from superimposing a virtual image on an obstacle from an eye point, can be provided.
The display apparatus according to this invention, as shown in the basic block diagram of FIG. 1, further includes detecting means 32 for detecting a display position information indicating a display position of a virtual image from the eye point and the storage device 21b for storing a distance information of superimposed viewing stores the distance information of superimposed viewing correspondingly to the display position information, and the judging means 21a1 judges based on the distance information of superimposed viewing read out from the storage device 21b correspondingly to the display position information detected by the detecting means 32 for detecting a display position information, in the display apparatus as mentioned above.
In the display apparatus for a vehicle as mentioned above, when a display position information indicating a display position of a virtual image from an eye point is detected by the detecting means 32, the distance information of superimposed viewing corresponding to the display position information is read out from the storage device 21b and whether or not the virtual image is superimposed on the obstacle is judged by the judging means 21a1, based on the distance information of superimposed viewing. Thus, a display position information indicating a display position of a virtual image from an eye point is detected and projecting a picture onto the member of projection is stopped when an obstacle which is seen in a front view and is superimposed by the virtual image in the view from the eye point is detected based on the distance information of superimposed viewing corresponding to the display position information, so that superimposing a virtual image on an obstacle from an eye point is prevented even if a position of the eye point is moved. Therefore, a display apparatus for a vehicle without hindering from seeing a front view by superimposing a virtual image can be provided, even if a position of an eye point is changed by replacing the other driver with a different physique to move a driver seat forward/backward or have a different sitting height.
The display apparatus according to this invention, as shown in the basic block diagram of FIG. 1, further includes detecting means 50 for detecting an information of external condition to judge whether or not it is bright at the outside of the vehicle, and the image source displays an image of the infrared camera which can take the image ahead the vehicle at night, and the judging means 21a1 judges whether or not it is bright at the outside of the vehicle based on the information of the external condition detected by the detecting means 50, and the control means 21a2 controls to stop the projection of the picture when it is judged by the judging means 21a1 that it is bright at the outside of the vehicle, in the display apparatus as mentioned above.
In the display apparatus for a vehicle as mentioned above, the judging means 21a1 judges whether or not it is bright at the outside of the vehicle based on the information of the external condition detected by the detecting means 50, and the control means 21a2 controls to stop projecting a picture taken by the infrared camera onto the member of projection when it is judged by the judging means 21a1 that it is bright at the outside of the vehicle. When the display apparatus for a vehicle according to this invention is applied to a night vision system for driving at night, light of a streetlight with large brightness or a headlight of an oncoming vehicle may cover a virtual image so that a vehicle driver can not perceive an obstacle easily. However, in the display apparatus mentioned above, judging whether or not it is bright at the outside of the vehicle based on the information of the external condition and controlling to stop projecting a picture onto the member of projection when it is judged that it is bright at the outside of the vehicle, hindering from perceiving an obstacle by a virtual image can be prevented. Therefore, a vehicle driver can perceive an obstacle securely and driving visibility at night can be supported securely.
The above and other objects and features of this invention will become more apparent from the following description taken in conjunction with the accompanying drawings.